The status of the blood-ocular barriers, both the blood-retinal through the vascular endothelium of the capillaries and the blood-retinal through the pigment epithelium of retina, are being studied after subjecting rats and monkeys to a variety of stresses. These stresses include acute hypertension induced by arterial perfusion and acute diabetes induced by the injection of streptozotocin. In each case a marker dye such as fluorescein is injected intravenously, the eyes are enucleated and freeze-dried and then studied by fluorescence microscopy.